1. Technical Field
The present invention relates to a projector.
2. Related Art
There is a known projector of related art in which light outputted from a light source apparatus is modulated by a light modulator in accordance with image information and the modulated light is projected through a projection lens onto a projection surface.
JP-A-2013-88743 discloses a projector including a controller having a normal mode in which a light source and a light modulator are cooled by controlling the speed of rotation of a cooling fan and an auxiliary mode in which the speed of rotation of the cooling fan is controlled to differ from the speed of rotation in the normal mode based on the temperature in an exterior enclosure after the projector is activated. In a situation in which constituent members of the projector expand due to an increase in the temperature of the light source and therefore shift a projection position, the configuration described above quickly achieves a balanced state in the enclosure by using the auxiliary mode to shorten the period required to adjust the projection position.
FIGS. 6A to 6C are cross-sectional views diagrammatically showing a schematic configuration of a projector 9 of related art. FIG. 6A shows a state immediately after projection starts. FIG. 6B shows a first state after the projection starts. FIG. 6C shows the following state after the projection starts. FIG. 7 shows a change in the projection position due to an increase in temperature in the projector 9 of related art. In FIG. 7, the horizontal axis (X axis) represents elapsed time (in minutes) immediately after the projection starts, and the vertical axis (Y axis) represents the amount of change in the projection position immediately after the projection starts. FIG. 7 shows a result of an experiment conducted by the present inventor. The graph in FIG. 7 is drawn with reference to the projection position at the time when the projection starts (0 minutes). The Y axis shown in FIG. 7 represents the amount of change in the projection position in the form of the number of shifted pixels, but the number of pixels and other parameters are not numerically shown.
The projector 9 of related art includes an illumination unit 90, which has an optical system including a light source apparatus 901, an image formation unit 91, which has an optical system including a light modulator 911, a projection unit 92, which has an optical system including a projection lens 921, and a frame 93, which fixes the illumination unit 90 and the projection unit 92, as shown in FIGS. 6A to 6C. The image formation unit 91 is coupled to the projection unit 92, and the projection unit 92 to which the image formation unit 91 has been coupled is coupled to the illumination unit 90.
A plurality of fixing portions 902, which are formed all around the exterior of the illumination unit 90, fix the illumination unit 90 to the frame 93. The projection unit 92 is also fixed to the frame 93 via a plurality of fixing portions 922. Each of an enclosure that forms the illumination unit 90 and the frame 93 is formed of a synthetic resin member.
In general, a projector has a heat generation source, such as a power supply and a light source apparatus. After the light source apparatus is turned on to start projection, the temperature of each constituent member that forms the projector gradually increases from a start temperature equal to the temperature in the environment where the projector is installed. Each constituent member that forms the projector is primarily made of a synthetic resin and therefore expands/contracts as the temperature changes, and the modulus of elasticity of the synthetic resin also changes with temperature.
In the projector 9 immediately after the projection starts, the temperature of each constituent member is equal to the temperature in the environment, and the constituent member does not deform due to expansion and is held in an intended position thereof, as shown in FIG. 6A. In this state, an image (modulated light) is precisely projected in a projection position set on a screen (not shown).
In the first stage after the projection starts, however, when the temperature of the illumination unit 90 including the light source apparatus 901 increases, the enclosure that forms the illumination unit 90 expands and the modulus of elasticity of the enclosure decreases. The expansion, the decrease, and the self-weight of the projection unit 92 deform the projection unit 92 in such a way that it is gradually inclined downward, as shown in FIG. 6B. FIG. 7 shows that the projection position gradually shifts downward immediately after the projection starts. Thereafter, when the temperature of the frame 93 increases, the projection unit 92 now conversely deforms in such a way that it is inclined upward, as shown in FIG. 6C. FIG. 7 shows that after the projection starts, the projection position shifts downward, reaches the lowest position in about 6 minutes, and then conversely shifts upward.
As described above, when the temperature of the illumination unit 90 first increases, the projection position undesirably shifts downward, and when the temperature of the frame 93 increases after a time lag, the projection position undesirably shifts upward. In either case, after the projection starts, the constituent members expand due to an increase in temperature and deform accordingly, undesirably resulting in a change in (displacement of) the projection position.
A projector that accommodates deformation of constituent members due to a change in temperature to suppress displacement in the projection position has therefore been desired.